Our goal is to elucidate the development and natural history of experimental atherosclerosis in the rat as induced by denuding the endothelial lining of arteries by means of a Fogarty balloon catheter. The effects of both a single and successive repeated denudations will be studied in a new strain of genetically obese rat which develops endogenous hyperlipidemia and spontaneous hypertension and in the nonobese siblings of such rats which become hypertensive but not hyperlipidemic. The use of these two animal types along with normal Wistar rats (normotensive and normolipidemic) should permit us to compare and evaluate the roles played by high blood pressure and by elevated plasma lipids, individually and in combination, in the genesis of atherosclerosis. Since both these items constitute high risk factors in the development of coronary heart disease, the results should have bearing on an important health problem in the human.